Junna Saito is assigned to a boys' school where there is a 'genius in anal development', a.k.a. God Hand. Junna, who has a beautiful ass that everyone recognises, is spotted by him and has his anal twitching done to her! Moreover, his true identity is the honour student Chihiro Hoshino. Junna can't believe the normally quiet Chihiro, but he develops sexual zones he didn't know existed until now - and he's in for a surprise. 斎藤純和が赴任した男子校には「ア○ル開発の天才」通称ゴッドハンドがいるという。 誰もが認める美尻の持ち主である純和は彼に目をつけられ、お尻のアナをいじられてしまった!! しかもその正体は優等生の星野千尋。 普段は大人しい千尋のSっぷりが信じられない純和だが、今まで知らなかった性感帯を開発されていく――。 そのうえ、子供っぽく懐いてくる千尋がかわいくなっちゃって!?